Nope. GTA "only" sold 7.6 million on 360. How much of that would have transferred to the PS3 along with PS3 HW sales if DLC had been multiplat from the beginning? Certainly not 50%, maybe 1 million, but let's say 2 million. The 360 gap got to over 8.5 million at its peak, take off a very optimistic 2 million and you have 6.5 million peak 360 lead.
The FFXIII effect remains to be seen. Going by the Americas pre-order chart PS3 has a big FFXIII lead in the country where 360 is the queen (Wii is the king). So it seems FFXIII didn't really drag too many FF fans from PS2 to 360, at least not in America. But let's be super-optimistic and say another 2 million. As of today 360>PS3 by 5.9 million, whack off that 2 million for GTA and we have 3.9 million, whack off another 2 million for FFXIII and we still have 360 ahead by 1.9 million. Even with major optimism 360 would still be ahead of PS3 today. I seriously doubt GTA IV and FFXIII were responsible for a 4 million console shift towards the 360.
What was responsible for the shift towards 360 was a 1 year head start and a ridiculously pricey PS3.
And then of course there was Wii to throw a huge bucket of cold water over the PS3, and throw a spanner in the works of 360's quest for global domination. Of course both HD consoles are living quite well in Wii's shadow, thankfully.
“The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.” - Bertrand Russell
"When the power of love overcomes the love of power, the world will know peace."
Jimi Hendrix
